/***
 * ASM: a very small and fast Java bytecode manipulation framework
 * Copyright (c) 2000-2005 INRIA, France Telecom
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the copyright holders nor the names of its
 *    contributors may be used to endorse or promote products derived from
 *    this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
 * THE POSSIBILITY OF SUCH DAMAGE.
 */
package clojure.asm;

/**
 * A dynamically extensible vector of bytes. This class is roughly equivalent to
 * a DataOutputStream on top of a ByteArrayOutputStream, but is more efficient.
 *
 * @author Eric Bruneton
 */
public class ByteVector{

/**
 * The content of this vector.
 */
byte[] data;

/**
 * Actual number of bytes in this vector.
 */
int length;

/**
 * Constructs a new {@link ByteVector ByteVector} with a default initial
 * size.
 */
public ByteVector(){
	data = new byte[64];
}

/**
 * Constructs a new {@link ByteVector ByteVector} with the given initial
 * size.
 *
 * @param initialSize the initial size of the byte vector to be constructed.
 */
public ByteVector(final int initialSize){
	data = new byte[initialSize];
}

/**
 * Puts a byte into this byte vector. The byte vector is automatically
 * enlarged if necessary.
 *
 * @param b a byte.
 * @return this byte vector.
 */
public ByteVector putByte(final int b){
	int length = this.length;
	if(length + 1 > data.length)
		{
		enlarge(1);
		}
	data[length++] = (byte) b;
	this.length = length;
	return this;
}

/**
 * Puts two bytes into this byte vector. The byte vector is automatically
 * enlarged if necessary.
 *
 * @param b1 a byte.
 * @param b2 another byte.
 * @return this byte vector.
 */
ByteVector put11(final int b1, final int b2){
	int length = this.length;
	if(length + 2 > data.length)
		{
		enlarge(2);
		}
	byte[] data = this.data;
	data[length++] = (byte) b1;
	data[length++] = (byte) b2;
	this.length = length;
	return this;
}

/**
 * Puts a short into this byte vector. The byte vector is automatically
 * enlarged if necessary.
 *
 * @param s a short.
 * @return this byte vector.
 */
public ByteVector putShort(final int s){
	int length = this.length;
	if(length + 2 > data.length)
		{
		enlarge(2);
		}
	byte[] data = this.data;
	data[length++] = (byte) (s >>> 8);
	data[length++] = (byte) s;
	this.length = length;
	return this;
}

/**
 * Puts a byte and a short into this byte vector. The byte vector is
 * automatically enlarged if necessary.
 *
 * @param b a byte.
 * @param s a short.
 * @return this byte vector.
 */
ByteVector put12(final int b, final int s){
	int length = this.length;
	if(length + 3 > data.length)
		{
		enlarge(3);
		}
	byte[] data = this.data;
	data[length++] = (byte) b;
	data[length++] = (byte) (s >>> 8);
	data[length++] = (byte) s;
	this.length = length;
	return this;
}

/**
 * Puts an int into this byte vector. The byte vector is automatically
 * enlarged if necessary.
 *
 * @param i an int.
 * @return this byte vector.
 */
public ByteVector putInt(final int i){
	int length = this.length;
	if(length + 4 > data.length)
		{
		enlarge(4);
		}
	byte[] data = this.data;
	data[length++] = (byte) (i >>> 24);
	data[length++] = (byte) (i >>> 16);
	data[length++] = (byte) (i >>> 8);
	data[length++] = (byte) i;
	this.length = length;
	return this;
}

/**
 * Puts a long into this byte vector. The byte vector is automatically
 * enlarged if necessary.
 *
 * @param l a long.
 * @return this byte vector.
 */
public ByteVector putLong(final long l){
	int length = this.length;
	if(length + 8 > data.length)
		{
		enlarge(8);
		}
	byte[] data = this.data;
	int i = (int) (l >>> 32);
	data[length++] = (byte) (i >>> 24);
	data[length++] = (byte) (i >>> 16);
	data[length++] = (byte) (i >>> 8);
	data[length++] = (byte) i;
	i = (int) l;
	data[length++] = (byte) (i >>> 24);
	data[length++] = (byte) (i >>> 16);
	data[length++] = (byte) (i >>> 8);
	data[length++] = (byte) i;
	this.length = length;
	return this;
}

/**
 * Puts an UTF8 string into this byte vector. The byte vector is
 * automatically enlarged if necessary.
 *
 * @param s a String.
 * @return this byte vector.
 */
public ByteVector putUTF8(final String s){
	int charLength = s.length();
	if(length + 2 + charLength > data.length)
		{
		enlarge(2 + charLength);
		}
	int len = length;
	byte[] data = this.data;
	// optimistic algorithm: instead of computing the byte length and then
	// serializing the string (which requires two loops), we assume the byte
	// length is equal to char length (which is the most frequent case), and
	// we start serializing the string right away. During the serialization,
	// if we find that this assumption is wrong, we continue with the
	// general method.
	data[len++] = (byte) (charLength >>> 8);
	data[len++] = (byte) charLength;
	for(int i = 0; i < charLength; ++i)
		{
		char c = s.charAt(i);
		if(c >= '\001' && c <= '\177')
			{
			data[len++] = (byte) c;
			}
		else
			{
			int byteLength = i;
			for(int j = i; j < charLength; ++j)
				{
				c = s.charAt(j);
				if(c >= '\001' && c <= '\177')
					{
					byteLength++;
					}
				else if(c > '\u07FF')
					{
					byteLength += 3;
					}
				else
					{
					byteLength += 2;
					}
				}
			data[length] = (byte) (byteLength >>> 8);
			data[length + 1] = (byte) byteLength;
			if(length + 2 + byteLength > data.length)
				{
				length = len;
				enlarge(2 + byteLength);
				data = this.data;
				}
			for(int j = i; j < charLength; ++j)
				{
				c = s.charAt(j);
				if(c >= '\001' && c <= '\177')
					{
					data[len++] = (byte) c;
					}
				else if(c > '\u07FF')
					{
					data[len++] = (byte) (0xE0 | c >> 12 & 0xF);
					data[len++] = (byte) (0x80 | c >> 6 & 0x3F);
					data[len++] = (byte) (0x80 | c & 0x3F);
					}
				else
					{
					data[len++] = (byte) (0xC0 | c >> 6 & 0x1F);
					data[len++] = (byte) (0x80 | c & 0x3F);
					}
				}
			break;
			}
		}
	length = len;
	return this;
}

/**
 * Puts an array of bytes into this byte vector. The byte vector is
 * automatically enlarged if necessary.
 *
 * @param b   an array of bytes. May be <tt>null</tt> to put <tt>len</tt>
 *            null bytes into this byte vector.
 * @param off index of the fist byte of b that must be copied.
 * @param len number of bytes of b that must be copied.
 * @return this byte vector.
 */
public ByteVector putByteArray(final byte[] b, final int off, final int len){
	if(length + len > data.length)
		{
		enlarge(len);
		}
	if(b != null)
		{
		System.arraycopy(b, off, data, length, len);
		}
	length += len;
	return this;
}

/**
 * Enlarge this byte vector so that it can receive n more bytes.
 *
 * @param size number of additional bytes that this byte vector should be
 *             able to receive.
 */
private void enlarge(final int size){
	int length1 = 2 * data.length;
	int length2 = length + size;
	byte[] newData = new byte[length1 > length2 ? length1 : length2];
	System.arraycopy(data, 0, newData, 0, length);
	data = newData;
}
}
